1. Field of the Invention
The present invention relates to a micro electric generator based on piezoelectric material, a method of providing the same, and an electric generating device.
2. Description of Related Art
Piezoelectric effect is the ability of some materials to generate an electric field or electric potential in response to applied mechanical stress. Piezoelectric materials can be applied into numerous uses such as bio-medical usages, electrical vehicles, wind power plants, hydroelectric power plants, wireless sensors, personal electronics, micro-electro-mechanical systems (MEMS), nano-electro-mechanical systems (NEMS), etc. Piezoelectric materials include barium titanate (BaTiO3), lead zirconate-titanate (PZT), quartz, tourmaline, Rochelle salts, tantalates, niobates, aluminum nitride (AlN), gallium nitride (GaN), and zinc oxide (ZnO), etc.
Based on such piezoelectric materials, a micro electric generator is enabled to convert mechanical energy into electrical energy.
Generally, a conventional micro electric generator may be in a form of stacked-layers in which a piezoelectric layer is sandwiched between two flat electrodes.
U.S. Pat. No. 3,976,898, for example, disclosed a micro electric generator comprising a three-layered [electrode/piezoelectric element/electrode] structure which can convert mechanical stress into electric energy. In CN101575082A, a micro wind turbine generator based on wind-induced vibration mechanism and piezoelectric effect is disclosed, which has a multi-layered structure comprising a piezoelectric layer and metal electrodes.
Reference with FIG. 1, a conventional micro electric generator 10 is shown, which comprises electrode layers 11 and a piezoelectric layer 12 interposed between the electrode layers 11. While a force 13 is applied to the surface of the electrode layer 11, the piezoelectric layer 12 sandwiched between two electrode layers 11 converts the force 13 into electrical energy.
However, the generated current density of such micro electric generator with multi-layered structure is usually unsatisfactory, and the manufacturing cost is high. In this regard, it is desirable to provide an improved technique toward micro electric generator to achieve superior current density and lower the manufacturing cost.